NCE to an NP
NORMAL CURVE EQUIVALENT
The Normal Curve Equivalent (NCE) was developed specifically to compute averages and calculate differences when comparing test scores. Like NPs, NCEs range from 1 to 99, but unlike NPs, NCEs are an equal-interval scale and can be treated arithmetically. Thus, NCEs are useful in determining trends or calculating gains and losses across scores within a content area. NCEs are also the preferable score when averaging scores or when comparing gains, losses, or trends across content areas. Frequently, NCE averages or differences are converted to NPs, since NPs and NCEs coincide at the 1st, 50th, and 99th points on each scale. A look-up table is used to cross-reference NPs and NCEs, found on page 23 of the Beyond the Numbers brochure and presented below.
Look-Up Table Between National Percentiles and Normal Curve Equivalents (NCEs) National Percentile 99 98 97 96 95 94 93 92 91 90 89 88 87 86 85 84 83 82 81 80 79 78 77 76 75 74 73 72 71 70 69 68 67
Mean NCE 99 93 90 87 85 83 81 80 78 77 76 75 74 73 72 71 70 69 68 68 67 66 66 65 64 64 63 62 62 61 60 60 59
National Percentile 66 65 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34
Mean NCE 59 58 58 57 56 56 55 55 54 54 53 53 52 52 51 51 50 49 49 48 48 47 47 46 46 45 45 44 44 43 42 42 41
National Percentile 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
Mean NCE 41 40 40 39 38 38 37 36 36 35 34 34 33 32 32 31 30 29 28 27 26 25 24 23 22 20 19 17 15 13 10 7 1
NATIONAL STANINE
The National Stanine is a scale that divides the scores of the norm group into nine units. A Stanine is similar to Scale Scores and NCEs in that it is an equal-interval scale and can be treated arithmetically. Stanines are single-digit numbers, so they lack precision in describing scores. For example, a student with a National Stanine of 5 could have a NP as low as 41 and as high as 59. Guide to Test Interpretation
Page 9 Copyright © 2014 by CTB/McGraw-Hill LLC. All rights reserved.
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The Normal Curve Equivalent (NCE) was developed specifically to compute averages and calculate differences when comparing test scores. Like NPs, NCEs range from 1 to 99, but unlike NPs, NCEs are an equal-interval scale and can be treated arithmetically. Thus, NCEs are useful in determining trends or calculating gains and losses across scores within a content area. NCEs are also the preferable score when averaging scores or when comparing gains, losses, or trends across content areas. Frequently, NCE averages or differences are converted to NPs, since NPs and NCEs coincide at the 1st, 50th, and 99th points on each scale. A look-up table is used to cross-reference NPs and NCEs, found on page 23 of the Beyond the Numbers brochure and presented below.
Look-Up Table Between National Percentiles and Normal Curve Equivalents (NCEs) National Percentile 99 98 97 96 95 94 93 92 91 90 89 88 87 86 85 84 83 82 81 80 79 78 77 76 75 74 73 72 71 70 69 68 67
Mean NCE 99 93 90 87 85 83 81 80 78 77 76 75 74 73 72 71 70 69 68 68 67 66 66 65 64 64 63 62 62 61 60 60 59
National Percentile 66 65 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34
Mean NCE 59 58 58 57 56 56 55 55 54 54 53 53 52 52 51 51 50 49 49 48 48 47 47 46 46 45 45 44 44 43 42 42 41
National Percentile 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
Mean NCE 41 40 40 39 38 38 37 36 36 35 34 34 33 32 32 31 30 29 28 27 26 25 24 23 22 20 19 17 15 13 10 7 1
NATIONAL STANINE
The National Stanine is a scale that divides the scores of the norm group into nine units. A Stanine is similar to Scale Scores and NCEs in that it is an equal-interval scale and can be treated arithmetically. Stanines are single-digit numbers, so they lack precision in describing scores. For example, a student with a National Stanine of 5 could have a NP as low as 41 and as high as 59. Guide to Test Interpretation
Page 9 Copyright © 2014 by CTB/McGraw-Hill LLC. All rights reserved.
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